A mass air-flow sensor is used on fuel-injected vehicles to tell the computer how much air is going into the engine. Discover why a mass air flow sensor must be removed in order to be checked with help from an auto mechanic in this free video on auto parts.

Video transcription

How do you clean or check a mass air flow sensor? A mass air flow sensor is used on fuel injected vehicles to tell the computer how much air is going into the engine. Usually, it's mounted between the air filter assembly and the intake. It has an electrical connection going to it, and it'll be screwed in to this plenum work here, so that it's in the air flow. Now, to check it for cleaning purposes or for inspection purposes, it needs to be removed. So the first thing you want to do is you want to carefully disconnect the electrical connection by lifting up on the release tab and pulling it off and kind of set that aside. And then there'll be a couple of screws holding it in place. Sometimes there'll be a security screw. In this case, there was a security torque screw, and so you want to make sure that you have the appropriate tool for that. So you take the screws out, and then you want to carefully pull straight up. Now, a mass air flow sensor will have one or more very, very fine wires. These wires are usually made out of platinum because platinum has very measurable resistance characteristics. And what we're measuring, in this case, is the resistance through the wire as air flows across it. And so if the air...if there's more air or if the air is cooler, it requires more voltage to keep the wire at a constant voltage, and so the computer interprets that as a...an indication of how much air is moving into the motor. So once it's removed, you can use a commercially available carburetor cleaner, and you can spray the wires. And this will remove any oxidation that might have built up on the wire that would affect its accuracy. And then you want to let this air-dry. You don't want to wipe it with anything because, again, you might end up damaging the wires. So once you've sprayed it with the carb cleaner, you want to let it air-dry and then you can reinstall it. Once you've removed and cleaned the mass air flow sensor, you're going to want to check it. Now, different mass air flow sensors from different manufacturers are going to have different acceptable ranges, but effectively, what you're looking to do is check the resistance between certain pins on the connector. And when you do that, you're going to want to get an ohms range that falls within the spec that the manufacturer specifies. In this case, we're getting 11.8 milliohms, which is fine for that particular wire. If you're outside of that range or you're getting no resistance at all, then the mass air flow sensor is most likely damaged and needs to be replaced. If, however, your resistance ranges are appropriate, then the mass air flow sensor should be fine with a good cleaning, and it can then be reinstalled.